Antihypertensive properties of a nitric oxide-releasing naproxen derivative in two-kidney, one-clip rats

Vascular Inflammation in Hypertension: Targeting Lipid Mediators Unbalance and Nitrosative Stress

Arterial hypertension is a worldwide public health threat. High Blood Pressure (BP) is commonly associated with endothelial dysfunction, nitric oxide synthases (NOS) unbalance and high peripheral vascular resistance. In addition to those, inflammation has also been designated as one of the major components of BP increase and organ damage in hypertension. This minireview discusses vascular inflammatory triggers of high BP and aims to fill the existing gaps of antiinflammatory therapy of hypertension. Among the reasons discussed, enhanced prostaglandins rather than resolvins lipid mediators, immune cell infiltration and oxidative/nitrosative stress are pivotal players of BP increase within the inflammatory hypothesis. To address these inflammatory targets, this review also proposes new concepts in hypertension treatment with non-steroidal antiinflammatory drugs (NSAIDs), nitric oxide-releasing NSAIDs (NO-NSAIDs) and specialized proresolving mediators (SPM). In this context, the failure of NSAIDs in hypertension treatment seems to be associated with the reduction of endogenous NO bioavailability, which is not necessarily an effect of all drug members of this pharmacological class. For this reason, NO-releasing NSAIDs seem to be safer and more specific therapy to treat vascular inflammation in hypertension than regular NSAIDs.

Naproxen and Diclofenac Attenuate Atorvastatin-induced Preconditioning of the Myocardium

Statins reduce infarct size (IS) in ischemia-reperfusion injury of the myocardium. Inhibition of cyclooxygenase-2 (COX-2) attenuates this benefit. We investigated the effect of two widely used non-selective non-steroidal anti-inflammatory drugs (NSAIDs) with different degree of anti-COX-2 activity on atorvastatin-mediated preconditioning. Wistar rats received oral atorvastatin (10 mg∙kg^-1∙day^-1), naproxen (10 mg∙kg^-1∙day^-1), diclofenac (8 mg∙kg^-1∙day^-1), atorvastatin+naproxen, atorvastatin+diclofenac or water for three days. Hearts were then excised and perfused in the Langendorff system. Area at risk (AR) and IS were determined after 30 min of regional ischemia and 120 min of reperfusion. Atorvastatin reduced IS by 51.3% compared with controls (14.7 ± 3.9% vs. 30.2 ± 4.6% of the AR; P < 0.001). Naproxen and diclofenac alone did not alter IS compared to control. Diclofenac completely abrogated atorvastatin-mediated protection of the myocardium. Naproxen significantly attenuated but did not eliminate the IS reducing the effect of atorvastatin when compared with controls (P = 0.038). The difference in IS between the atorvastatin+naproxen group and the atorvastatin+diclofenac group showed a strong trend in reaching statistical significance (P = 0.058), but was not found to be significant. Our results suggest relatively small, but noticeable differences among non-selective NSAIDs in their potential to attenuate statin-mediated preconditioning.

Nonsteroidal Anti-Inflammatory Therapy: A Journey Toward Safety

The efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) against inflammation, pain, and fever has been supporting their worldwide use in the treatment of painful conditions and chronic inflammatory diseases until today. However, the long-term therapy with NSAIDs was soon associated with high incidences of adverse events in the gastrointestinal tract. Therefore, the search for novel drugs with improved safety has begun with COX-2 selective inhibitors (coxibs) being straightaway developed and commercialized. Nevertheless, the excitement has fast turned to disappointment when diverse coxibs were withdrawn from the market due to cardiovascular toxicity. Such events have once again triggered the emergence of different strategies to overcome NSAIDs toxicity. Here, an integrative review is provided to address the breakthroughs of two main approaches: (i) the association of NSAIDs with protective mediators and (ii) the design of novel compounds to target downstream and/or multiple enzymes of the arachidonic acid cascade. To date, just one phosphatidylcholine-associated NSAID has already been approved for commercialization. Nevertheless, the preclinical and clinical data obtained so far indicate that both strategies may improve the safety of nonsteroidal anti-inflammatory therapy.

Treatment with a nitric oxide-donating NSAID alleviates functional muscle ischemia in the mouse model of Duchenne muscular dystrophy

In patients with Duchenne muscular dystrophy (DMD) and the standard mdx mouse model of DMD, dystrophin deficiency causes loss of neuronal nitric oxide synthase (nNOSμ) from the sarcolemma, producing functional ischemia when the muscles are exercised. We asked if functional muscle ischemia would be eliminated and normal blood flow regulation restored by treatment with an exogenous nitric oxide (NO)-donating drug. Beginning at 8 weeks of age, mdx mice were fed a standard diet supplemented with 1% soybean oil alone or in combination with a low (15 mg/kg) or high (45 mg/kg) dose of HCT 1026, a NO-donating nonsteroidal anti-inflammatory agent which has previously been shown to slow disease progression in the mdx model. After 1 month of treatment, vasoconstrictor responses to intra-arterial norepinephrine (NE) were compared in resting and contracting hindlimbs. In untreated mdx mice, the usual effect of muscle contraction to attenuate NE-mediated vasoconstriction was impaired, resulting in functional ischemia: NE evoked similar decreases in femoral blood flow velocity and femoral vascular conductance (FVC) in the contracting compared to resting hindlimbs (ΔFVC contraction/ΔFVC rest = 0.88±0.03). NE-induced functional ischemia was unaffected by low dose HCT 1026 (ΔFVC ratio = 0.92±0.04; P>0.05 vs untreated), but was alleviated by the high dose of the drug (ΔFVC ratio = 0.22±0.03; P<0.05 vs untreated or low dose). The beneficial effect of high dose HCT 1026 was maintained with treatment up to 3 months. The effect of the NO-donating drug HCT 1026 to normalize blood flow regulation in contracting mdx mouse hindlimb muscles suggests a putative novel treatment for DMD. Further translational research is warranted.

Blood pressure effects of naproxcinod in hypertensive patients

The blood pressure (BP) effects of naproxcinod and naproxen were assessed in an 8-week, double-blind, crossover study in 131 hypertensive patients aged 50 to 74 years. Patients received naproxcinod 750 mg twice daily or naproxen 500 mg twice daily, then the alternate treatment, each for 14 days, with placebo run-in/washout before each active treatment period and 24-hour ambulatory BP monitoring conducted before and after each active treatment period. Mean change from baseline in average 24-hour systolic BP (SBP) after 2 weeks of treatment numerically favored naproxcinod 750 mg twice daily (least-squares [LS] mean for naproxcinod minus naproxen: -1.6 mm Hg; P=.12). Post hoc analyses showed statistically significant SBP differences favoring naproxcinod for the 8 elapsed hours (LS mean: -4.4 mm Hg; P<.0001) and the 24 hours following morning dosing (LS mean: -2.4 mm Hg; P=.006). Naproxcinod may be a beneficial alternative for patients with osteoarthritis requiring nonsteroidal anti-inflammatory drugs.

Treatment strategies for osteoarthritis patients with pain and hypertension

Out of 100 patients with osteoarthritis (OA), almost 40 have a concomitant diagnosis of hypertension. Nonsteroidal anti-inflammatory drugs (NSAIDs) and cyclooxygenase-2 (COX-2) inhibitors may trigger a rise in blood pressure (BP), which is more marked in patients with established hypertension. NSAIDs and COX-2 inhibitors attenuate the antihypertensive effect of several antihypertensive agents. Frequent BP controls are needed in treated hypertensive patients who are concomitantly receiving NSAIDs or COX-2 inhibitors because even a small increase in BP may be associated with an important rise in the risk of major cardiovascular complications. In meta-analyses, an increase in systolic BP of 5mmHg was associated with a 25% higher risk of cardiovascular events. These data have been confirmed in randomized studies with rofecoxib and celecoxib, where a modest increase in BP was associated with a significantly higher risk of cardiovascular disease. There is emerging evidence that the COX-inhibiting nitric oxide donator (CINOD) class is promising in the treatment of patients with OA. Naproxcinod, the first CINOD investigated in clinical trials, is composed of the traditional NSAID naproxen covalently bound to the nitric oxide (NO)-donating moiety butanediol mono-nitrate (BDMN). The molecule has the potential to provide a sustained release of NO. In clinical studies, naproxcinod prevented the BP rise in normotensive and hypertensive patients observed with naproxen. The BP benefit of naproxcinod over naproxen was greater in patients concomitantly receiving angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers. These investigational data suggest that naproxcinod is a valuable alternative to NSAIDs and COX-2 inhibitors for treatment of OA patients.

Treatment of osteoarthritis in hypertensive patients

IMPORTANCE OF THE FIELD

Osteoarthritis and hypertension commonly co-exist. Treatment of osteoarthritis in hypertensive patients is a therapeutic challenge due to the adverse effects of some analgesics, especially non-steroidal anti-inflammatory drugs (NSAIDs), on blood pressure. Even small drug-induced rises in blood pressure due to therapy may significantly increase cardiovascular risk in these patients if sustained over the long term. Patients treated with certain classes of antihypertensive agent may be at particular risk of deterioration in blood pressure control with NSAID therapy. NSAIDs may also increase cardiovascular risk due to mechanisms other than by raising blood pressure.

AREAS COVERED IN THIS REVIEW

We discuss the management of osteoarthritis in the hypertensive patient, review the evidence for the effects of paracetamol and NSAIDs on blood pressure and discuss novel therapeutic strategies for osteoarthritis that might diminish this problem. A literature search was undertaken in PubMed including the years 1980 - 2009.

WHAT THE READER WILL GAIN

Insight will be gained into the complexity of treating patients with co-existent osteoarthritis and hypertension and into possible new approaches to treating osteoarthritis symptoms effectively in these patients while minimising any adverse impact on blood pressure control.

TAKE HOME MESSAGE

There are ways to minimise the adverse impact of treatment of osteoarthritis on blood pressure control in hypertensive patients.

Markedly reduced toxicity of a hydrogen sulphide-releasing derivative of naproxen (ATB-346)

BACKGROUND AND PURPOSE

Hydrogen sulphide is an important mediator of gastric mucosal defence. The use of non-steroidal anti-inflammatory drugs continues to be limited by their toxicity, particularly in the upper gastrointestinal tract. We evaluated the gastrointestinal safety and anti-inflammatory efficacy of a novel hydrogen sulphide-releasing derivative of naproxen, ATB-346 [2-(6-methoxy-napthalen-2-yl)-propionic acid 4-thiocarbamoyl-phenyl ester].

EXPERIMENTAL APPROACH

The ability of ATB-346 versus naproxen to cause gastric damage was evaluated in healthy rats and in rats with compromised gastric mucosal defence. Effects on the small intestine and on the healing of ulcers were also assessed. The ability of ATB-346 to inhibit cyclooxygenase-1 and 2 and to reduce inflammation in vivo was also evaluated.

KEY RESULTS

ATB-346 suppressed gastric prostaglandin E(2) synthesis as effectively as naproxen, but produced negligible damage in the stomach and intestine. In situations in which the gastric mucosa was rendered significantly more susceptible to naproxen-induced damage (e.g. ablation of sensory afferent nerves, inhibition of endogenous nitric oxide or hydrogen sulphide synthesis, co-administration with aspirin, antagonism of K(IR)6.x channels), ATB-346 did not cause significant damage. Unlike naproxen and celecoxib, ATB-346 accelerated healing of pre-existing gastric ulcers. In a mouse airpouch model, ATB-346 suppressed cyclooxygenase-2 activity and inhibited leukocyte infiltration more effectively than naproxen. ATB-346 was as effective as naproxen in adjuvant-induced arthritis in rats, with a more rapid onset of activity. Unlike naproxen, ATB-346 did not elevate blood pressure in hypertensive rats.

CONCLUSIONS AND IMPLICATIONS

ATB-346 exhibits anti-inflammatory properties similar to naproxen, but with substantially reduced gastrointestinal toxicity.

Efficacy, safety, and tolerability of the cyclooxygenase-inhibiting nitric oxide donator naproxcinod in treating osteoarthritis of the hip or knee

OBJECTIVE

Naproxcinod, a cyclooxygenase-inhibiting nitric oxide donator antiinflammatory drug, was evaluated in this phase 2, double-blind, randomized, parallel group study to determine its optimal dose in patients with osteoarthritis (OA).

METHODS

In total 543 patients with OA of the hip or knee were randomized to receive naproxcinod 750 mg once daily (qd), 750 mg twice daily (bid), 1125 mg bid, rofecoxib 25 mg qd, or placebo for 6 weeks. The primary efficacy variable was the within-patient change from baseline to the average of Weeks 4 and 6 in WOMAC pain subscale score. Treatment-group differences were compared using ANCOVA with factors for treatment and country, and baseline pain subscale score as a covariate. Safety endpoints included vital signs and adverse events. Treatment-group differences in mean change from baseline to Week 6 in systolic blood pressure (SBP) were compared using an ANCOVA with treatment and country as fixed factors and baseline SBP as covariate.

RESULTS

All active treatments showed statistically significant reductions in WOMAC pain score compared to placebo (p<or=0.02). Naproxcinod was well tolerated. The 750 mg bid dose appeared to have the best balance of benefit versus safety. All 3 naproxcinod doses showed a reduction in SBP, while an increase was shown for rofecoxib. The changes for the naproxcinod groups were statistically significantly better compared to rofecoxib (p<or=0.02).

CONCLUSION

This dose-finding study identified naproxcinod 750 mg bid as the upper dose for further therapeutic confirmatory clinical trials. Naproxcinod at all doses decreased mean SBP compared to an increase with rofecoxib.

Treatment of patients with hypertension and arthritis pain: new concepts

Arthritis pain often occurs concurrently with hypertension and other cardiovascular risk factors. Treating patients with hypertension who have arthritis and other painful conditions can be a challenge because of potential risks associated with the agents commonly used to treat pain and inflammation. Hypertension is associated with endothelial dysfunction and decreased bioavailability of nitric oxide (NO). Naproxcinod, an investigational drug, is the first in a new class of agents called cyclooxygenase-inhibiting NO donators. They differ from traditional nonsteroidal anti-inflammatory drugs in their ability to donate NO, a signaling molecule known to have potentially beneficial effects on the vasculature and the gastrointestinal tract. Naproxcinod, by donating NO, offers a therapeutic option that might mitigate the negative blood pressure effects and adverse gastrointestinal effects associated with traditional arthritis therapies. This article reviews some preliminary preclinical and clinical studies of key safety data of an investigational new NO-donating anti-inflammatory agent.

WB1106, a novel nitric oxide-releasing derivative of telmisartan, inhibits hypertension and improves glucose metabolism in rats

Angiotensin converting enzyme (ACE) inhibitors usually cause severe coughing and intolerance while antagonists for angiotensin AT(1) receptor do not stimulate the production of nitric oxide (NO). NO has been shown to regulate arterial hypertension and insulin resistance. Hence, new hybrids of antagonist for angiotensin AT(1) receptor and a NO donor may have potent anti-hypertensive effect and regulate glucose metabolism and insulin resistance. Herein, the effects of [6-(nitrooxymethyl)pyridin-2-yl] methyl 4'-[1-(1,7'-dimethyl-2'-propyl-1H,3'H-2,5'-bibenzo[d]imidazol-3'-yl)ethyl] biphenyl-2-carboxylate (WB1106), a novel NO-releasing derivative of telmisartan newly synthesized, on the vasocontraction, hypertension and diet-induced insulin resistance were examined in vitro using rat aortic strips and in normotensive and spontaneous hypertension rats (SHR rats). Apparently, WB1106 induced the vasorelaxation of contracted rat aortic strips in a dose- and time-dependent manner, which depended on the activity of guanylate cyclase, a characteristic of NO-related function. Furthermore, WB1106 reduced the contractile and blood pressure responses to angiotensin II, which relied on the release of telmisartan. Moreover, treatment with WB1106 significantly reduced the blood pressure with similar potency to telmitarsan and increased the contents of cGMP in SHR rats. Therefore, WB1106 possesses both the angiotensin AT(1) receptor antagonist activity of telmisartan and the NO-releasing property of a 'slow NO donor'. Importantly, in contrast to equimolar telmisartan, treatment with WB1106 significantly attenuated body weight gains and improved glucose tolerance in high-fat and carbohydrate-fed rats, reflecting a synergistic effect of NO and telmisartan. Potentially, WB1106 may be a potent anti-hypertensive drug for treatment of hypertension and diabetes-related cardiovascular diseases in the clinic.

Building a better aspirin: gaseous solutions to a century-old problem

The gastrointestinal adverse effects of nonsteroidal anti-inflammatory drugs (NSAIDs) have been recognized since shortly after the introduction of aspirin to the marketplace over a century ago. However, the underlying pathogenesis of NSAID-induced gastropathy remains incompletely understood. Advances in understanding some of the factors that contribute to the mucosal injury have provided clues for the development of safer NSAIDs. The inhibitory effects of nitric oxide (NO) on NSAID-induced leukocyte adherence were exploited in the development of NO-releasing NSAIDs. As well as eliciting less gastrointestinal damage than conventional NSAIDs, these drugs do not elevate blood pressure and show anti-inflammatory effects, additional to those of the parent drugs. Modification of other drugs in a similar manner (i.e., NO-releasing derivatives) has similarly resulted in more effective drugs. More recently, hydrogen sulphide-releasing derivatives of NSAIDs and of other drugs, have been developed, based on the observed ability of H(2)S to reduce inflammation and pain in experimental models. H(2)S-releasing NSAIDs produce negligible gastric damage and exhibit enhanced anti-inflammatory potency as compared to the parent drugs. The NO-NSAIDs and H(2)S-releasing NSAIDs represent examples of new anti-inflammatory drugs with greatly reduced toxicity and improved therapeutic activity, both created through the concept of exploiting the beneficial effects of endogenous gaseous mediators.

PHARMACOKINETICS AND PHARMACODYNAMICS OF A NITRIC OXIDE-RELEASING DERIVATIVE OF ENALAPRIL IN MALE BEAGLES

1. Pharmacological compounds that release nitric oxide (NO) have been useful tools in the evaluation of the broad role of NO in physiopathology and therapeutics. The present study compared the pharmacokinetics and pharmacodynamics of enalapril and an NO-releasing enalapril molecule (NCX899) in conscious male beagles. The effects of both enalapril and NCX899 in the arterial hypertension and bradycardia induced by acute NO inhibition in anaesthetized dogs were also investigated. 2. Dogs received either NCX899 (4 micromol/kg, i.v.) or enalapril (4 micromol/kg, i.v.), after which plasma concentrations of the analytes and metabolites were quantified by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). 3. In the NCX899 group, the area under the time-course curve (AUC(0-24h)) was 29.18 +/- 4.72, 229.37 +/- 51.32 and 5159.23 +/- 514.88 microg.h/L for the analytes nitro-enalapril, enalapril and enalaprilat, respectively. In the enalapril group, the AUC(0-24h) was 704.53 +/- 158.86 and 4149.27 +/- 847.30 microg.h/L for the analytes enalapril and enalaprilat, respectively. Statistical analysis of data from both groups showed a significant difference for the analyte enalapril, but not for enalaprilat. Moreover, NCX899 and enalapril were equally effective in inhibiting the activity of serum angiotensin-converting enzyme. 4. In anaesthetized dogs, i.v. administration of the NO synthase (NOS) inhibitor N(G)-nitro-l-arginine methyl ester (l-NAME; 0.1-10 mg/kg) significantly elevated arterial blood pressure, with concomitant bradycardia. The compound NCX899 significantly attenuated both arterial hypertension and bradycardia, whereas enalapril had no significant effect. 5. In conclusion, the present results showed that the NO-releasing derivative of enalapril NCX899 presents a pharmacokinetic/pharmacodynamic relationship similar to its parent compound enalapril. Moreover, NCX899 (but not enalapril) was effective in protecting against the cardiovascular changes induced by acute NOS inhibition.

Gastrointestinal safety and anti-inflammatory effects of a hydrogen sulfide-releasing diclofenac derivative in the rat

BACKGROUND & AIMS

Gastrointestinal damage caused by nonsteroidal anti-inflammatory drugs (NSAIDs) remains a significant clinical problem. Hydrogen makes an important contribution to mucosal defense, and NSAIDs can suppress its synthesis. In this study, we evaluated the gastrointestinal safety and anti-inflammatory effects of a novel "HS-NSAID" (ATB-337) that consists of diclofenac linked to a hydrogen sulfide-releasing moiety.

METHODS

The gastrointestinal injury-inducing effects of single or repeated administration of diclofenac versus ATB-337 were compared in rats, as were their effects on prostaglandin synthesis and cyclooxygenase-1 and -2 activities. The ability of these drugs to reduce carrageenan-induced paw edema and to elicit leukocyte adherence to the vascular endothelium (intravital microscopy) were also examined in rats.

RESULTS

Diclofenac (10-50 micromol/kg) dose-dependently damaged the stomach, while ATB-337 did not. Repeated administration of diclofenac caused extensive small intestinal damage and reduced hematocrit by 50%. ATB-337 induced >90% less intestinal damage and had no effect on hematocrit. Diclofenac, but not ATB-337, elevated gastric granulocyte infiltration and expression of tumor necrosis factor alpha, lymphocyte function-associated antigen 1, and intercellular adhesion molecule 1. ATB-337 inhibited cycloxygenase-1 and cyclooxygenase-2 activity as effectively as diclofenac. ATB-337 did not induce leukocyte adherence, whereas diclofenac did, and was more potent at reducing paw edema.

CONCLUSIONS

An HS-NSAID spares the gastric mucosa of injury despite markedly suppressing prostaglandin synthesis. This effect may be related to hydrogen sulfide-mediated inhibition of tumor necrosis factor-alpha expression and of the leukocyte adherence to vascular endothelium normally induced by cyclooxygenase inhibitors.

Endothelial cell dysfunction: can't live with it, how to live without it

Endothelial cell dysfunction is emerging as an ultimate culprit for diverse cardiovascular diseases and cardiovascular complications of chronic renal diseases, yet the definition of this new syndrome, its pathophysiology, and therapy remain poorly defined. Here, I summarize some molecular mechanisms leading from hyperhomocystinemia, elevated asymmetric dimethylarginine, and advanced glycolation end product-modified protein level to the proatherogenic, prothrombogenic, and proinflammatory endothelial phenotype and offer a model of endothelial dysfunction based on the interconnectedness of diverse functions. Finally, several therapeutic strategies to prevent and correct endothelial dysfunction are discussed in the light of uncertainty of their action modulated by the endothelial dysfunction per se.

Nitric Oxide (NO)-Releasing Naproxen (HCT-3012 [(S)-6-Methoxy-α-methyl-2-naphthaleneacetic Acid 4-(Nitrooxy)butyl Ester]) Interactions with Aspirin in Gastric Mucosa of Arthritic Rats Reveal a Role for Aspirin-Triggered Lipoxin, Prostaglandins, and NO in Gastric Protection

Administration of selective and nonselective cyclooxygenase (COX)-2 inhibitors to rheumatoid arthritis patients taking low doses of acetylsalicylic acid (ASA) for cardiovascular prevention associates with increased risk of gastrointestinal bleeding. The present study was undertaken to investigate whether administration of HCT-3012 [(S)-6-methoxy-alpha-methyl-2-naphthaleneacetic acid 4-(nitrooxy)butyl ester], a nitric oxide (NO)-releasing derivative of naproxen, exacerbates gastric mucosal injury in arthritic rats administered low doses of ASA. Our results demonstrated that while treating arthritic rats with a dose of 30 mg/kg/day ASA causes detectable mucosal injury, but had no effect on arthritis score and interleukin-6 plasma levels, coadministration of naproxen (10 mg/kg/day) and celecoxib (30 mg/kg/day), in combination with ASA from day 7 to day 21, attenuates arthritis development (P <0.01 versus arthritis alone), but markedly enhanced gastric mucosal damage caused by ASA (P <0.01 versus ASA alone). In contrast, coadministration of HCT-3012 (15 mg/kg/day) significantly attenuated arthritis development, because HCT-3012 was equally or more effective than naproxen and celecoxib in attenuating local and systemic inflammation (P >0.001 versus arthritis) without exacerbating gastric mucosal injury caused by ASA. Arthritis development associates with gastric COX-2 induction, mRNA and protein, and enhanced gastric prostaglandin E2 (PGE2) synthesis (P <0.01 versus control rats). Although all treatments, including celecoxib, were effective in reducing gastric PGE2 synthesis, administering arthritic rats with ASA resulted in a significant increase in gastric content of aspirin-triggered lipoxin (ATL), a COX-2-derived lipid mediator that regulates proinflammatory responses at the neutrophils/endothelial interface. Administering arthritic rats with naproxen and celecoxib abrogates ATL formation induced by ASA although enhanced neutrophils accumulate into the gastric mucosa (P <0.01 versus ASA alone). In contrast, whereas HCT-3012 inhibited ATL formation, it did not increase neutrophil recruitment into the gastric microcirculation. Collectively, these data indicate that HCT-3012 derived from NO has the potential to compensate for inhibition of PGE2 and ATL and to protect the gastric mucosa by limiting the recruitment of neutrophils. These data suggest that HCT-3012 might be a safer alternative to nonsteroidal anti-inflammatory drugs and coxibs in rheumatic patients that take low doses of ASA.

Pharmacology and potential therapeutic applications of nitric oxide-releasing non-steroidal anti-inflammatory and related nitric oxide-donating drugs

This review examines the biological significance, therapeutic potential and mechanism(s) of action of a range of nitric oxide-releasing non-steroidal anti-inflammatory drugs (NO-NSAID) and related nitric oxide-releasing donating drugs (NODD). The slow release of nitric oxide (NO) from these compounds leads to subtle changes in the profile of pharmacological activity of the parent, non-steroidal anti-inflammatory drugs (NSAID). For example, compared with NSAID, NO-NSAID cause markedly diminished gastrointestinal toxicity and improved anti-inflammatory and anti-nociceptive efficacy. In addition, nitroparacetamol exhibits hepatoprotection as opposed to the hepatotoxic activity of paracetamol. The possibility that NO-NSAID or NODD may be of therapeutic benefit in a wide variety of disease states including pain and inflammation, thrombosis and restenosis, neurodegenerative diseases of the central nervous system, colitis, cancer, urinary incontinence, liver disease, impotence, bronchial asthma and osteoporosis is discussed.

Nitric oxide-releasing aspirin decreases vascular injury by reducing inflammation and promoting apoptosis

Endothelial dysfunction, defined as a deficit in the bioavailability of nitric oxide (NO), occurs as sequelae of many vascular diseases; however, the utility of supplementing NO to obviate the extent of disease is understudied. Here, we examined if prolonged treatment with an NO-releasing form of aspirin (NO-ASA) can influence neointimal remodeling of femoral arteries of hypercholesterolemic ApoE (-/-) mice. Treatment of ApoE (-/-) mice with NO-ASA, but not aspirin (ASA), improved neointimal remodeling post-injury. NO-ASA treatment increased lumen diameters and reduced intimal-to-medial ratios of injured femoral arteries compared with ASA- or vehicle-treated mice. The reduction in lumen diameter in NO-ASA-treated mice was associated with a marked reduction in CD45-positive inflammatory cells and an increased number of TUNEL-positive cells. Thus, NO-ASA, by virtue of releasing NO, can reduce vascular inflammation and promote apoptosis during vascular remodeling associated with neointimal thickening.

Potential cardioprotective actions of no-releasing aspirin

The use of low doses of aspirin on a daily basis has increased greatly in the past 20 years, based on observations that it can significantly reduce the risk of heart attacks and strokes. However, aspirin can also cause severe damage to the stomach. A modified version of aspirin that releases nitric oxide has been developed that seems to offer important advantages over its 103-year-old parent--namely, improved protection for the heart without the unwanted effects on the stomach.

Vasorelaxant effect of nitric oxide releasing steroidal and nonsteroidal anti-inflammatory drugs

The effect of several nitric oxide releasing-non-steroidal anti-inflammatory drugs (NO-NSAID) and nitroprednisolone on blood vessel relaxation in vitro and in vivo was studied. Nitroflurbiprofen (NOF; EC(50), 688.8+/-93.8 microM), nitroaspirin (NOA; EC(50), 57.9+/-6.5 microM), nitroparacetamol (NOPARA; EC(50), 71.5+/-14.6 microM) and nitroprednisolone (EC(50), 15.1+/-1.4 microM) caused concentration-related relaxation of noradrenaline (NA)-contracted rat aortic rings. All NO releasing compounds tested were approximately three orders of magnitude less potent than sodium nitroprusside (SNP, EC(50), 35.7+/-3.5 nM). The vasorelaxant effect of NOF and NOPARA in the rat aorta was potentiated by zaprinast (5 microM) and reduced by ODQ (5 microM). Flurbiprofen and paracetamol (100 microM) caused minimal (<10%) relaxation of the rat aorta and did not affect the response to SNP. The effect of NOF was unchanged in the presence of L-NAME (100 microM; EC(30), 181.8+/-35.1 microM cf. EC(30), 125.1+/-17.0 microM, P>0.05) but increased by removal of the endothelium (EC(30), 164.3+/-26.3 microM cf. EC(50), 688.8+/-93.8 microM, P<0.05). NOF (0.1 - 50 microM) produced a small but not concentration-related vasodilation of the NA-preconstricted (i.e. "high tone") perfused rat mesentery preparation (cf. SNP, EC(30), 4.4+/-0.7 microM). In contrast, NOF (1 - 100 microM) produced concentration-related vasodilation of the "high tone" perfused rat kidney with an EC(50) of 33.1+/-4.4 microM. Neither NOF (74 mg kg(-1), i.p.) nor NOA (91.9 mg kg(-1), i.p.) nor equimolar doses of flurbiprofen (50 mg kg(-1), i.p.) or aspirin (50 mg kg(-1), i.p.) affected mean arterial blood pressure (MAP) or heart rate (HR) of pentobarbitone-anaesthetized rats over a 1 h period. NO-NSAID relax blood vessels in vitro by an NO-dependent mechanism. The absolute vasorelaxant effect of NO releasing drug varies greatly with the choice of compound and between blood vessel preparations.

Vasorelaxant effects of a nitric oxide-releasing aspirin derivative in normotensive and hypertensive rats

1. Nonsteroidal anti-inflammatory drugs have been reported to exacerbate hypertension and to interfere with the effectiveness of some anti-hypertensive therapies. In this study, we tested the effects of a gastric-sparing, nitric oxide-releasing derivative of aspirin (NCX-4016) on hypertension in rats. 2. Hypertension was induced by administering L-NAME in the drinking water (400 mg l(-1)). Groups of rats were treated daily with aspirin, NCX-4016 or vehicle. 3. NCX-4016 significantly reduced blood pressure relative to the aspirin-treated group over the 2-week period of treatment. Aspirin and, to a lesser extent, NCX-4016 suppressed whole blood thromboxane synthesis. 4. In anaesthetized rats, acute intravenous administration of NCX-4016 caused a significant fall in mean arterial pressure in hypertensive rats, but was devoid of such effects in normotensive controls. 5. In vitro, NCX-4016 relaxed phenylephrine-pre-contracted aortic rings obtained from both normotensive and hypertensive rats, and significantly reduced their responsiveness to the contractile effects of phenylephrine. 6. These results suggest that NCX-4016 reduces blood pressure in hypertensive rats, not simply through the direct vasodilatory actions of the nitric oxide released by this compound, but also through possible interference with the effects of endogenous pressor agents. These properties, added to its anti-thrombotic effects, suggest that NCX-4016 may be a safer alternative to aspirin for use by hypertensive patients.

Nonsteroidal anti-inflammatory drugs, low-dose aspirin, and potential ways of reducing the risk of complications

Use of nonsteroidal anti-inflammatory drugs (NSAIDs) is associated with an annual incidence of 1-2% of gastrointestinal (GI) complications, which may be fatal in some cases. Low-dose aspirin is also associated with an increased risk of upper GI bleeding, but the increase is about three times lower than that found with common NSAIDs. Misoprostol (600-800 microg/day) reduces the incidence of complications in non-aspirin NSAID users. Co-therapy with antisecretory drugs (proton pump inhibitors, PPIs) also reduces the risk of GI bleeding in high-risk patients taking NSAIDs and/or low-dose aspirin. Another way of reducing the incidence of GI complications is to use the highly selective cyclo-oxygenase 2 (COX-2) inhibitors. The GI safety of nitric oxide NSAIDs (NO-NSAIDs) has been demonstrated extensively in experimental conditions and preliminary clinical studies. Epidemiological studies have also shown that nitric oxide donor drugs reduce the risk of upper GI bleeding, which might be important in patients receiving low-dose aspirin.